In the process of retreading tires, it is known to mount the tire on a "curing rim" for support during the procedures of buffing, retreading, curing, and the like. Such curing rims must be readily insertable into a tire initially, and readily removable from the tire after completion of the work, and must securely hold the tire during the work processes which include inflation of the tire so as to force the casing into satisfactory engagement with a curing mold which surrounds the tire at this time.
A curing rim suitable for this use is shown in U.S. Pat. No. 3,133,317 to C. E. Branick. It comprises a pair of half-rims or sleeves in axial apposition yet capable of limited relative rotation, together with locking hooks and lugs effective in a pre-determined relative rotated position of the sleeves to prevent axial separation therebetween. The sleeves have outward flanges to engage the bead of a tire. Handle rods are shown for enabling manual rotation of one sleeve relative to the other. In use, one sleeve is laid flat on a suitable support and the tire to be worked on is lifted and laid in the sleeve: the other sleeve is lifted and laid on the tire and first sleeve, and relatively rotated with respect thereto until the locking hooks and lugs are in engagement. The tire can then be placed in the mold, inflated, and retreaded in the usual manner.
While the structure just described is fully operative for its intended purpose, it suffers from certain imperfections. It is possible for the forces active during the procedures to cause reverse relative rotation between the sleeves, until the hooks and lugs are positionally disabled, allowing the sleeves to separate. Also to be borne in mind is the fact that the sleeves and the tires themselves, particularly in larger commercial sizes, are of considerable bulk and weight, and hence are difficult to lift and position, and moreover provide very considerable resistance to the relative rotation between the sleeves which is necessary for effective operation of the locking hooks and lugs.